[eng] The indiscriminate use of beta-lactams has considerably diminished their efficiency as a result of bacteria developing effective defense mechanisms against them. Recent pharmaceutical research has led to the synthesis of tricyclic â-lactam antibiotics known as 'tricyclic carbapenems' or 'trinems'. In this work, we studied the chemical reactivity, an essential property for antibiotic action, of trinems and found it to be similar to that of cephalosporins. Also, we elucidated the interaction pattern for sanfetrinem and 4â-methoxy trinem and compared it to that for classical â-lactams. The behavior of both trinems was found to be similar to that of penicillin G toward Staphylococcus aureus PC1, and that of cephalothin and imipenem toward Enterobacter cloacae P99.